Method and apparatus for dispensing liquids as an atomized spray

ABSTRACT

The invention provides exemplary methods and apparatus for dispensing liquids as an atomized spray. In one particularly preferably method, a liquid is dispensed as an atomized spray from a vibratable member having a front surface and a rear surface, with the member having at least one tapered hole between the surfaces for dispensing the liquid. The tapered hole has a larger cross-sectional area at the rear surface than at the front surface. The liquid is delivered from a supply container to the rear surface of the vibratable member in an amount sufficient to cover the hole with liquid. The vibratable member is then vibrated to dispense at least a portion of the liquid through the hole and from the front surface. Additional liquid is delivered from the supply container and to the rear surface in volumes that are substantially equal to the volumes dispensed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of U.S. patentapplication Ser. No. 08/163,850, filed on Dec. 7, 1993, which is acontinuation-in-part of U.S. patent application Ser. No. 07/726,777,filed on Jul. 8, 1991 (now abandoned), which is a continuation-in-partof U.S. patent application Ser. No. 07/691,584, filed on Apr. 24, 1991,now U.S. Pat. No. 5,164,740. The complete disclosures of all theseapplications are herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the fields of liquid spray andatomization of liquids of all kinds and, more specifically, findsutility in humidification and misting, industrial cleaning, surfacecoating and treatment, particle coating and encapsulating, fuelatomization, deodorization, disbursement of insecticides, aerosols, andmedical spray applications.

2. Description of Related Art

Many types of ultrasonic fluid ejection devices have been developed foratomizing of water or liquid fuel. These atomizers can be classifiedinto two groups. The first type atomizes liquid that forms a thin layeron an ultrasonically-excited plate. The first type is not capable ofejecting atomized fluid droplets. U.S. Pat. No. 3,738,574 describes anatomizer of this type.

The second type utilizes a housing defining an enclosed chamber. Thehousing includes a perforated membrane or a pinhole membrane as thefront wall of the chamber. The apparatus further includes a means tovibrate the membrane or a side wall of the chamber, typically by apiezoelectric element affixed to the front face of the chamber. Thepiezoelectric element oscillates the fluid in the chamber. As a result,pressure waves are generated in the chamber, forcing fluid through theopen pinholes. All the devices of the second type require fluid to bekept inside the chamber next to the discharge opening. When volatilefluids are used, problems arise. The volatile fluids escape through thedischarge opening. Hence, liquid may undesirably outflow from theopening. The discharge opening will clog, restricting or stoppingfurther discharge. These problems are prevalent with volatile fluidssuch as fuel, paint, or other coating materials. To overcome at leastsome of these problems, U.S. Pat. No. 4,533,082 uses a vacuum pump toensure that the liquid in the chamber is kept under negative pressure toprevent outflow.

Other variations of apparatus for ejecting atomized liquid, utilizingone of the above two types, are disclosed in U.S. Pat. Nos. 3,812,854,4,159,803, 4,300,546, 4,334,531, 4,465,234, 4,632,311, 4,338,576, and4,850,534.

Certain writing instruments, such as fountain pens, employ mechanismsfor controlling the flow of ink from a supply container to the writingtip of the pen.

SUMMARY OF THE INVENTION

The present invention provides an ejection device that includes a freeoscillating surface having microscopic tapered apertures of a selectedconical cross-sectional shape. A layer of fluid adheres in surfacetension contact with the oscillating surface. The apertures draw fluidinto their large openings and eject the fluid from their small openingsto a great distance. The ejection action is developed by the aperture,regardless of the amount of fluid in contact with the oscillatingsurface, and without any fluid pressure. Both sides of the oscillatingsurface are operating under the same ambient pressure. Therefore, theejection device can operate equally well in vacuum or high-pressureenvironments. The supplied liquid continuously adheres to the largeopening by surface tension. The film of fluid oscillates with thesurface while it is being drawn into the large opening of the apertureand ejected forwardly. This continues until all the fluid is drawn fromthe surface, leaving the surface dry and free of liquid during the timethat the device is not in use.

If the cross-section of the aperture is chosen with respect to the fluidto be ejected, the oscillation required to produce ejection is keptsmall, and the film of fluid on the oscillating surface appears to bedynamically at rest during ejection. By supplying only enough fluid tocontinuously form a thin film, in surface tension contact with theoscillating surface, to the side containing the large openings of thetapered apertures, neither clogging nor uncontrolled emission or leakagethrough the apertures occurs. The device can operate under any pressureconditions.

In an alternative embodiment, the invention provides an apparatus fordispensing liquids as an atomized spray. The apparatus preferablyincludes a vibratable member having a front surface, a rear surface, andat least one tapered hole extending therebetween. The tapered hole has alarger cross-sectional area at the rear surface than at the frontsurface. A means is provided for vibrating the member, and a supplycontainer is provided for holding the liquid to be dispensed. A means isprovided for delivering the liquid from the supply container and to therear surface of the vibratable member. A flow regulator is furtherincluded for regulating the flow of the liquid from the container and tothe vibratable member. The flow regulator is configured to allowdelivery of the liquid to the rear surface in volumes that aresubstantially equal to the volumes dispensed from the vibratable member.Preferably, the liquid is delivered to the rear surface of thevibratable member at a rate that is substantially equal to the rate ofthe liquid being dispensed from the front surface. In this way, the flowof liquid from the supply container and to the rear surface is regulatedso that neither insufficient nor excessive amounts of liquid aredelivered to the rear surface. In this manner, an optimal amount ofliquid is provided to the rear surface during operation of theapparatus.

In a preferable aspect, the flow regulator includes an air vent that isin fluid communication with the supply container. When open, the airvent allows air to flow into the supply container in volumes that aresufficient to replace the volumes that are delivered to the rearsurface. In this way, delivery of liquid to the rear surface can becontrolled by regulating the amount of air flowing to the supplycontainer. Preferably, opening and closing of the air vent is controlledby the liquid itself as it travels from the supply container and to therear surface. As liquid flows from the supply container, some of theliquid flows into and closes the air vent thereby preventing air fromentering the supply container. As liquid continues to flow from thecontainer, a vacuum is created in the container to prevent additionalflow of liquid from the container. Upon ejection of liquid from thevibratable member, liquid in the air vent flows to the rear surface toreplace the ejected liquid. In this way, the air vent is again opened toallow air to enter the container and to allow additional liquid to flowfrom the supply container.

In a further aspect, the supply container is preferably oriented in aposition that facilitates the flow of liquid from the container and tothe rear surface. In another aspect, the air vent is distanced from thesupply container at a distance sufficient to allow the liquid to bedelivered to the rear surface at a rate that is substantially equal tothe rate of liquid dispensed from the hole.

The invention further provides a method for dispensing liquid dropletsas an atomized spray, with the liquid being delivered from a supplycontainer. According to the method, liquid is delivered from the supplycontainer and to the rear surface of a vibratable member in an amountsufficient to cover a hole in the member with liquid. The liquid is heldin the hole by surface tension. The vibratable member is then vibratedto dispense at least a portion of the liquid through the hole, with theliquid being dispensed from a front surface of the member. Additionalliquid is delivered from the supply container and to the rear surface involumes that are held in surface tension contact to the rear surface ofthe vibratable member, i.e. the entire volume of liquid that isdelivered to the rear surface is held to the rear surface by surfacetension forces so that the delivered liquid will remain attached to therear surface until ejected. Preferably, the liquid is delivered to therear surface at a rate that is substantially equal to the rate of theliquid being dispensed from the front surface.

In an exemplary aspect, preselected volumes of air are exchanged withliquid from the supply container to deliver the additional volumes ofliquid to the rear surface. Preferably, the preselected volumes of airare sufficient to replace the volumes of liquid that are delivered fromthe supply container and to the rear surface. In this way, bycontrolling the supply of air volumes to the supply container, theamount of liquid delivered to the rear surface can be regulated.Preferably, the supply of air to the supply container is controlled byopening and closing an air vent that is in communication with the supplycontainer. In one aspect, the air vent is closed upon filling of the airvent with liquid from the supply container as the liquid flows towardthe rear surface of the vibratable member. As liquid is ejected from thevibratable member, liquid flows from the air vent and to the rearsurface to replace the ejected liquid, thereby opening the air vent andallowing air to flow into the supply container. In turn, the airsupplied to the container allows additional liquid to flow from thesupply container and the process is repeated until vibration of themember is ceased.

The rate of liquid dispensed from the vibratable member can widely varydepending on the number of apertures and the size of each aperture. Inone particular aspect which is not meant to be limiting, the liquid isan insecticide which is dispensed at a rate in the range ofapproximately 0.1 cm³ to 10 cm³ per hour, and more preferably at about0.5 cm³ to 2 cm³ per hour. Preferably, the insecticide is ejected fromthe front surface in droplets having a mean size in the range from 1 μmto 15 μm, and more preferably at about 3 μm to 10 μm. In another aspectwhich is not meant to be limiting, the liquid is a deodorant, usually anair freshener, which is dispensed at a rate of approximately 0.1 cm³ to10 cm³ per hour, and more preferably at about 1 cm³ to 2 cm³ per hour.Preferably, the deodorant is ejected from the front surface in dropletshaving a size in the range from 1 μm to 15 μm, and more preferably atabout 3 μm to 10 μm.

In another embodiment of the invention, an apparatus which isparticularly useful as an insecticizer or a deodorizer is provided. Theapparatus includes a housing having at least one ejection port and avibratable member within the housing. The vibratable member includes atapered hole that is aligned with the ejection port. A means is providedfor supplying liquid to a rear surface of the vibratable member, and ameans is provided in the housing for vibrating the member. The housingis conveniently configured to receive a liquid supply container forholding a deodorant or an insecticide. When connected to the supplycontainer, the apparatus can be placed at a strategic location andactuated to dispense the liquid. In a preferable aspect, a battery isemployed as a power source to vibrate the member, thereby allowing theapparatus to be placed in a variety of locations and to be leftunattended while dispensing liquid.

In another exemplary aspect, the apparatus is provided with a controllerfor controlling actuation of the vibratable member. Preferably, thecontroller is preprogrammed to cyclically actuate the vibratable memberaccording to a preselected ejection schedule. Such a configuration isparticularly useful when dispensing an insecticide which requirescareful control of the amount of insecticide that is dispensed into theatmosphere. In another preferable aspect, upon depletion of the liquidfrom the supply container, a refill supply container can be attached tothe housing and the apparatus reused. In still a further aspect, therefill container is provided with a pair of N size cell batteries whichserve as the power source to vibrate the member. The batteries areprovided with sufficient energy to eject the full content of the refill.

BRIEF DESCRIPTION OF THE DRAWINGS

The general purpose and advances of the present invention will be morefully understood hereinafter as a result of the detailed description ofthe preferred embodiments when taken in conjunction with the followingdrawings, in which:

FIG. 1 is a schematic illustration of a preferred embodiment of a deviceaccording to the present invention.

FIG. 2 is the schematic illustration of the present invention of FIG. 1shown in its oscillating configuration.

FIG. 3 is a top view of a vibrating surface according to the presentinvention.

FIG. 4 is a bottom view of a vibrating surface according to the presentinvention.

FIG. 5 is an enlarged cross-sectional view of the center area of themembrane shown in FIG. 2 and labelled “5”.

FIG. 6 is an enlarged elevational view of the center area of thevibrating surface of the present invention showing a preferred apertureshape.

FIG. 7 is a schematic illustration of the fluid characteristic within atapered aperture during half of an oscillation cycle.

FIG. 8 is a schematic illustration of the fluid characteristic with atapered aperture during half of an oscillation cycle.

FIG. 9 is a side view of an alternate preferred embodiment of the fluidejection device according to the present invention.

FIG. 10 is a front view of the fluid ejection device of FIG. 9.

FIG. 11 is an enlarged cross-sectional side view of the free end of thefluid ejection device of FIG. 9.

FIG. 12 illustrates the ejector of FIG. 9 provided with a fluid supplysystem.

FIG. 13 illustrates an alternative apparatus for preventing accidentaloverflow in the fluid supply system of FIG. 12.

FIG. 13A illustrates a further alternative apparatus for preventingaccidental overflow in a fluid supply system.

FIG. 14 illustrates the ejector of FIG. 9 provided with an alternativefluid supply system.

FIG. 15 is an enlarged cross-sectional side view of the fluid supplytube of FIG. 14 including a discharge nozzle attached at a side wall ofthe supply tube.

FIG. 16 is an enlarged cross-sectional side view of the discharge nozzleof FIG. 14.

FIG. 17 is a side view of another alternative preferred embodiment ofthe fluid ejection device according to the present invention.

FIG. 18 is a front view of the fluid ejection device of FIG. 17.

FIG. 19 is a schematic view of an apparatus for controlling delivery ofa liquid from a supply container.

FIG. 20 is a schematic view of an alternative apparatus for controllingdelivery of a liquid from a supply container.

FIG. 21 is a perspective view of an exemplary dispensing apparatushaving a flow regulator for regulating the flow of liquid to avibratable member that is used to dispense the liquid.

FIG. 22 is a top view of the dispensing apparatus of FIG. 21.

FIG. 22A is a cutaway view of FIG. 22 taken along lines A—A.

FIG. 22B is a cross-sectional view of FIG. 22 taken along lines B—B.

FIG. 23 is an exploded view of a distal portion of the apparatus of FIG.21.

FIG. 24 is a side view of the dispensing apparatus of FIG. 21.

FIG. 24A is a cutaway view of the dispensing apparatus of FIG. 24 takenalong lines A—A.

FIG. 24B is an enlarged view of the region B—B of the dispensing unit ofFIG. 24A.

FIG. 25 is a perspective view of an exemplary dispensing apparatushaving a housing enclosing a vibratable member.

FIG. 26 illustrates the dispensing apparatus of FIG. 25 with a topportion of the housing removed.

INTRODUCTION

The present invention provides a new fluid ejection device that isespecially advantageous in applications that require ejection of fluiddroplets without fluid pressure and without a propellant and in ambientpressure environments.

A particularly important application for the present invention isindustrial spray systems. The ejector is capable of ejecting viscoseliquid such as paint and coating materials without the use of compressedair.

The use of air as a propellant in paint spray application causesoverspray, in that part of the paint droplets escape to the atmosphereand cause air pollution. The transfer efficiency, that is, thepercentage amount of coating material, such as paint, that reaches thetarget, is significantly increased when ejection is without air.

Another important application of the present invention is for consumerproducts such as deodorant and hair spray. The use of propellants inconventional aerosols, commonly known as volatile organic chemicals(VOCs), has a negative effect on the environment and on human health.There is an ongoing trend to find ways to atomize fluid without usingsuch propellant gases.

The present invention provides a device that ejects fluid frommicroscopic tapered apertures. The fluid is transported to the ejectingsurface at the large opening of the tapered aperture. A cohesiveattraction force (surface tension) exclusively causes the liquid toadhere to the tapered aperture. The solid/fluid interaction of the fluidwith the tapered aperture wall causes fluid to be drawn into the largeopening of the aperture and ejected from its small opening. Thisejection action is attributed to the geometry of the aperture, as wellas the fluid characteristics such as viscosity, density, and elasticity.The fluid supply to the surface is tightly controlled to preventoverflow of liquid from the supply side of the oscillating surface. Aflow control valve or a two-way valve is provided to control the amountof fluid that is transported to the surface. The valve may have abuilt-in electrical contact that activates oscillation simultaneouslywith the flow of fluid.

During ejection, fluid is supplied to the oscillating surface from adischarge nozzle that is in close proximity to the oscillating surface.The fluid is held by surface tension forces in the small gap between thefront face of the fluid supply nozzle and the oscillating surface. Whenthe fluid supply is stopped, the surface with the tapered apertures isallowed to oscillate for a period of time sufficient for the aperturesto draw all the fluid from the oscillating surface and the gap. When notin use, the gap, as well as the oscillating surface and the aperture,remain free of fluid.

The discharge nozzle is preferably made of elastomer material having acut through its thickness. The cut is normally closed due to theelasticity of the elastomer. The cut opens under slight pressure whenfluid is transported from the supply container. This arrangement keepsthe fluid in the container hermetically sealed during periods of nonuse.

An electronic wave generator with a circuit that can turn theoscillating action on and off sequentially at a very high speed ispreferred. The ratio of the “on” period versus the “off” period controlsthe duty cycle of ejection and, therefore, the ejection mean flow rate.Maximum flow is achieved when the oscillator is continuously “on”.

Fluid is preferably supplied to the oscillating surface at a rate thatis lower than the maximum ejection rate of the aperture. If the fluidsupply exceeds the maximum ejection rate of the apertures, excessivefluid may overflow from the supply side of the oscillating surface. Whenthe fluid used is paint or ink, overflow is undesirable. To preventoverflow, a system to collect liquid overflow may be used. This systemincludes a ring provided with a slot at its circumference which isconnected to a pump. If fluid accidentally escapes from the oscillatingsurface and reaches the slot, it is drawn and returned to the supplycontainer.

Another method of preventing accidental overflow is provided by anelectronic flow control valve. It has been found that as the amount ofliquid over the surface increases, the current draw by the piezoelectricelement decreases. If the current draw reaches a predetermined levelwhich indicates that an overflow is about to occur, the electroniccircuit transmits a signal to the flow control valve to reduce the flowof liquid to the surface. Thereby, overflow is avoided.

A further method of preventing accidental overflow is provided by a flowregulator that regulates the flow of liquid from a supply container tothe oscillating surface. The flow regulator includes an air vent that isin communication with the supply container. By closing the air vent, airis prevented from entering the supply container which in turn creates avacuum in the container to prevent liquid from flowing from thecontainer. By having at least some of the liquid within the containerconfigured to flow into the air vent, operation of the air vent can becontrolled by the liquid itself as it travels to the oscillatingsurface. As liquid is dispensed by the oscillating surface, liquid isdrained from the air vent and flows to the oscillating surface to openthe air vent and allow air into the container. In this manner, airenters into the supply container in volumes that are substantially equalto liquid volumes dispensed from the oscillating surface and at a ratesubstantially equal to the rate of ejection. Such a configuration allowsfor an optimal amount of liquid to automatically be delivered to theoscillating surface upon operation of the device.

DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENTS

Referring now to FIG. 1, it will be seen that the fluid ejection device10 of the present invention comprises a vibrating surface 12 having aperimeter area 14 and a center area 16. The perimeter 14 of vibratingsurface 12 is affixed to an oscillator 18 which may, for example, bepiezoceramic. The center area 16 of vibrating surface 12 is providedwith a planar surface 15 through which there are apertures 22. Theportion of center 15 having the apertures is in surface tension contactwith a fluid film 19 at the back side of planar surface 15 to produce anejection of fluid droplets 20.

The oscillatory motion of the vibrating surface 12 is shown in FIG. 2.It will be seen therein that the perimeter 14 of the vibrating surface12, by virtue of its contact with the oscillator 18, oscillates in avertical direction, as viewed in FIG. 2, with an oscillatingcharacteristic shown in the graph at the rightmost portion of FIG. 2. Asalso seen in FIG. 2, the center 16 of vibrating surface 12 oscillates atthe same frequency as the perimeter 14, but with a much largeramplitude, as seen in the graph on the leftmost portion of FIG. 2. Thegraphs of FIG. 2 are for purposes of illustration and are notnecessarily drawn to scale.

The significantly larger oscillation amplitude of the center of thevibrating surface in FIG. 2, as compared to the perimeter, is dueprimarily to two factors. One is the shape of the vibrating surface 12and the other is the frequency of oscillation that is selected foractivation of the oscillator 18. More specifically, vibrating surface 12is configured so that its cross-section is reduced toward the center.The vibrating surface configuration may be understood best by referringto FIGS. 2, 3, and 4, which illustrate a preferred embodiment thereof.The apertures 22 in vibrating surface 12 may be understood best byreferring to FIGS. 5 and 6. As seen therein, the center portion 15 (FIG.5) of the vibrating surface 12 is provided with apertures 22, eachcharacterized by a tapered wall 24, forming a large opening 26 on oneside of the center portion 15 and a small opening 28 on the oppositeside thereof. The thickness of the center portion 15 of the vibratingsurface 12 is preferably 0.003-inch. Each aperture 22 is positioned ator near the center of the vibrating surface and is circular in shapewith large opening 26 having a radius of 0.006-inch and the smallopening 28 thereof having a radius of 0.0025-inch.

The shape of vibrating surface 12 and, in particular, the reduction incross-section of the vibrating surface between its perimeter 14 (FIG. 3)and its center 16, is selected to provide a significant increase inamplitude of oscillation between the perimeter and the center ofvibrating surface 12. This increase in oscillation amplitude has beenfound to occur at particular frequencies of oscillation of the vibratingsurface 12 such as at the second harmonic of the natural oscillatingfrequency of the vibrating surface. In the preferred embodiment of thepresent invention, it is desirable to have a damping ratio of at least10 percent and to provide an amplitude ratio between the center area andthe perimeter of the vibrating surface of at least 10, depending uponthe voltage applied to the oscillator 18 and its mechanicalresponsiveness thereto.

When the center of the vibrating surface oscillates with an amplitudewhich exceeds a preselected threshold, fluid droplets are ejected fromaperture 22 (FIG. 1) at the frequency of oscillation of oscillator 18.Thus, by controlling the amplitude of the perimeter oscillation and,thus, the amplitude of the center oscillation so that it is either aboveor below this threshold ejection level, the ejection of fluid dropletsmay be readily controlled.

In one embodiment that has been reduced to practice, the oscillationamplitude is 0.001-inch at the perimeter. The frequency of oscillationis approximately 60,000 Hz, which corresponds to the second modalfrequency of the vibrating surface 12. The fluid droplet ejection level,that is, the level above which the amplitude of oscillation of thecenter 15 of the vibrating surface 12 causes fluid droplets to beejected therefrom, is approximately 0.0016-inch. The perimeteroscillation is adjusted so that the center oscillation varies inamplitude from cycle to cycle, so that it is just above the ejectionlevel and below the ejection level upon alternate cycles. The actualejection level threshold, that is, the actual oscillation amplitude ofthe center of the vibrating surface which causes the ejection of fluiddroplets, depends upon the characteristics of the fluid selected, aswell as the shape and dimensions of the aperture 22. In the particularpreferred embodiment shown herein, the ejection level is achieved usinggasoline.

As shown in FIGS. 7 and 8, fluid 19 continuously adheres throughsolid/fluid surface tension to the large opening 26 of aperture 22. Thefluid is compressed in the first half of the oscillation (FIG. 7) whenthe vibrating surface strokes toward the fluid and decompresses in thesecond half of the oscillation cycle (FIG. 8) when the vibrating surfacestrokes away from the fluid. Droplets are ejected each time theamplitude of oscillation of the aperture element 15 (FIG. 5) exceeds theejection level threshold. The number of droplets and spacingtherebetween are a function of the frequency of oscillation. In thepreferred embodiment hereof, at a 60,000-Hz oscillation frequency, ithas been found that when the ejection amplitude is continually above thethreshold level, droplets are attached to each other and form acontinuous stream. By altering the oscillation amplitude, such as byreducing it below the threshold level every second cycle, the dropletscan be separated. This feature is particularly advantageous in fuelinjection systems. It will be understood, however, that with selectedchanges in the shape of the vibrating surface 12, the characteristic ofthe fluid, and in the shape and dimensions of aperture 22, the selectedfrequency of operation may vary from that recited herein. Nevertheless,based upon the preferred embodiment disclosed herein, it will now beunderstood that ejection may be achieved by the present invention andthat, in fact, fluid-droplet ejection at frequencies exceeding 60,000 Hzis readily achieved.

FIG. 9 illustrates an alternate preferred embodiment of the fluidejection device 30 of the present invention which comprises a cantileverbeam 32 including a base portion 34 and a free end 36. The base portion34 is affixed to a piezoelectric oscillator 38. The free end 36 of thebeam 32 is provided with a planar surface through which there are ninemicroscopic tapered apertures. Fluid 42 is in contact with the free end36 through which droplets 44 are ejected.

FIG. 10 provides a front view of the fluid ejection device 30 and bestillustrates the apertures 40. FIG. 11 is an enlarged cross-sectionalside view of the fluid ejection device 30 showing the free end 36 incontact with the fluid 42. The large opening 46 of each aperture 40 isin surface tension contact with the fluid 42. The piezoelectric element38 (FIG. 9) produces high-frequency oscillations at the base end 34 ofthe beam 32. The planar surface 37 at the free end 36 oscillates at thesame frequency as the base 34, but with much greater amplitude. Suchoscillation of the free end 36 is due primarily to two factors: the beam32 is shaped such that its moment of inertia is reduced toward the freeend 36; and the induced frequency is substantially the natural frequencyof the beam 32.

The oscillation of the planar surface 37 produces cycles of pressurefluctuation at the interface between the fluid 42 and the surface 37 andinside the apertures 40 and, particularly, near the inside wall 48 ofeach aperture, is significantly more intense as compared to the pressurefluctuation near the planar surface 37. This characteristic isexclusively attributed to the conical cross-sectional geometry of theapertures 40. As a result, fluid cavitation is developed inside eachaperture 40 at an oscillation amplitude that is too small to dynamicallydisturb the fluid 42 near the planar surface 37. The cavitation insidethe aperture 40 produces a negative pressure that draws fluid from theplanar surface 37 into the large opening 46 of the aperture 40 andejects a stream of droplets 44 from its small opening 47 to a greatdistance. The ultrasonic oscillations do not break up or nebulize thefluid 42 at the surface 37, such fluid remaining dynamically at restduring the ejection of fluid 42 within the aperture 40. Ejectioncontinues until all the fluid 42 is drawn from the surface 37 andejected forwardly as droplets 44. In this preferred embodiment, thediameter of the large opening 46 of the aperture 40 is 0.006″ and thediameter of the small opening 47 is 0.0025″. The thickness of the planarsurface 37 is 0.003″ and the oscillation frequency is 50 kHz, which isthe third natural frequency of the beam 32.

Referring now to FIG. 12, the ejector 30 described in the specificationwith respect to FIGS. 9, 10, and 11 is now provided with a fluid supplysystem 50 that continuously transports fluid 51 to wet the oscillatingsurface 37 via a supply tube 53 ending at a supply nozzle 54. The fluid51 is transported to the surface 37 at a rate which is lower than themaximum ejection rate of the apertures 40 to prevent overflow of fluid42 from the supply side of the oscillating surface 37. A pinch valve 56controls delivery of the fluid 51 to the oscillating surface 37. Thefluid supply system 50 is connected to an electronic flow control valve52 which, in the preferred embodiment, is made by ICS sensors. The valve52 is connected to an electronic circuit that detects the amount ofliquid 42 on the oscillating surface 37. In the event of excessivedelivery of fluid, the oscillation amplitude decreases and the currentdraw by the piezoelectric element 38 decreases. A current sensor circuit39 senses the current draw and transmits an overflow signal 41 to theflow control valve 52 to reduce the delivery rate of liquid 51 to thesurface 37 until the amount of fluid returns to a normal level.

FIG. 13 illustrates an alternative apparatus for preventing fluidoverflow with the fluid supply system 50. An additional ring element 58including a slot 60 is installed near the oscillating surface 37 suchthat the slot 60 is positioned a predetermined distance from theboundary 62 of the fluid 42. The preferred ring element 58 ismanufactured by Clippard Instruments Laboratory, Inc. of Cincinnati,Ohio and is designated as Model No. 1022. The slot 60 is connected to asuction venturi pump (not shown) through an inlet 64. A suction venturipump, designated as Part No. 16480, is commercially available fromSpraying Systems Co. of Wheaton, Ill. In the event of overflow, theboundary 62 of the fluid 42 expands toward the ring 58 and returns tothe supply line 53.

FIG. 13A illustrates a further alternative apparatus 200 for preventingfluid overflow when dispensing liquid through vibrating taperedapertures in the manner previously described. The apparatus 200 operatesunder similar principles as those described in connection with theapparatus of FIG. 13. The apparatus 200 is particularly useful inapplications requiring high flow rates, e.g. gallons per hour, such aswith the injection of gasoline into an engine.

The apparatus 200 includes a housing 202, a delivery fluid path 204, anda return fluid path 206. An inlet port 208 is in communication with thedelivery fluid path 204 and an exit port 210 is in communication withthe return fluid path 206. Connected to the housing 202 by a bolt 212 orother securing member is a vibratable member 214. Vibration is providedto the member 214 by an ultrasonic transducer 216. Tapered apertures(not shown) are provided in the vibratable member 214 for ejectingliquid from the member 214 when vibrated by the transducer 216 in themanner previously described. The housing 202 further includes a liquidoutlet 204 b for supplying liquid to the vibrating member 214. A venturisuction arrangement 220 that is connected to the return fluid path 206and to the delivery fluid path 204.

Operation of the apparatus 200 is as follows. Fluid is supplied to theapparatus 200 through the inlet port 208. About two-thirds of the liquidflows through the path 204 and from the outlet 204 b to the vibratablemember 214. About one-third of the liquid flows through the venturisuction arrangement 220 causing intense suction at the fluid path 206.The fluid path 206 is in communication with the a flow path 218 so thatthe suction action can be transferred to an inlet opening 218 a of path218. The suction developed near the opening 218 a collects any excessliquid that has not been ejected and prevents overflow. The liquid thatis supplied to the venturi arrangement 220 and the liquid that returnsfrom the path 218 exit the apparatus 200 from port 210 where it can bedischarged or recirculated.

In a preferred embodiment, the apparatus 200 was installed in an airintake manifold of a small gasoline engine, model CV-14, from KohlerEngine, Kohler, Wis. The gasoline supply was disconnected from theengine carburetor and was instead connected to the supply port 208 ofapparatus 200. Apparatus 200 provides superior control over the supplyof atomized gasoline to the engine in comparison to a conventionalcarburetor. Preferably, the amount of gasoline and the time of ejectionis controlled by a conventional engine management system, such as modelLS-14 from Fuel Management Systems, Mendelein, Ill. It has been foundthat apparatus 200 is particularly advantageous for use in small twocycle internal combustion gasoline engines for reducing exhaustemission.

FIG. 14 shows the ejection device 30 of FIG. 9, further including analternative fluid supply system 70 and an electrical wave generator 71including a battery or external power inlet (not shown) to activate thepiezoceramic element. The ejector device 30 is preferably attached to aplatform 72 of the supply system 70 at the piezoelectric oscillator 38.The supply system 70 includes a fluid supply container 74 which ispreferably made from a flexible, disposable nylon material. A dischargenozzle 76 is affixed at a side wall of the supply container 74 providingfluid communication between fluid in the tube and the ejection device30. When force is applied to the side of the supply container 74, thefluid inside the supply container 74 is pressurized an forced throughthe discharge nozzle 76.

The supply system 70 further includes a discharge valve apparatus 80which is preferably attached to the platform 72. The preferred dischargeapparatus 80 includes a spring-loaded plunger 82 acting on the externalside wall of the supply container 74 against a rear opening of thedischarge nozzle 76 to prevent unwanted discharge of fluid from thesupply container 74. When the plunger 82 is released, fluid isdischarged toward the oscillating surface 37. Fluid enters into a gap 84between the nozzle 76 and the surface 37 and is held by surface tensioncontact. In the preferred embodiment this gap is 0.025″.

The alternative fluid supply system 70 additionally provides a means forapplying mechanical pressure 90 on the nylon container 74 to force thefluid through the nozzle 76. The pressure-applying means 90 includes apressure plate 92 pivotally attached to a torsion spring 94 for applyinga compressive force on a side wall 75 of the container 74. As shown inFIG. 14, the pressure plate 58 can be rotated clockwise to a releasedposition, facilitating the unloading and loading of fluid supplycontainers 74. In operation, the pressure plate 92 applies a continuouspressure of approximately 10 psi to the fluid inside the nylon container74.

FIG. 15 provides an enlarged cross-sectional side view of the supplycontainer 74 including an integrally-formed discharge nozzle 76 attachedat a side wall of the container 74. The nozzle includes a rear surface77 in fluid communication with fluid inside the supply container 74 anda front surface 79 positioned in close proximity to the vibrating freesurface 37.

FIG. 16 provides an enlarged cross-sectional side view of the dischargenozzle 76. As can be readily appreciated, a circumferential ridge 78formed around the discharge nozzle 76 ensures that the gap 84 ismaintained at its preferred distance. The nozzle 76 is preferably madeof an elastomer material and includes a cut 96 through part of itsthickness. The cut 96 is normally closed because of the naturalelasticity of the elastomer material. Fluid pressure applied to the rearside of the nozzle opening 98 forces the cut 96 to open and allowpassage of liquid to the oscillating surface 37. The discharge nozzle 76is designed to keep the fluid in the supply tube 76 hermetically sealedwhen the fluid ejection device 30 is not in use.

FIG. 17 illustrates another alternative preferred embodiment of thefluid ejection device wherein the oscillating surface comprises a curvedmember 100 with two piezoelectric elements 102 a, 102 b respectivelyaffixed to front surfaces 104 a, 104 b. The piezoelectric elements 102a, 102 b impart oscillations to a thin angled surface 106 locatedcentrally on the curved member 100, causing fluid 108 to be ejectedforwardly as a divergent stream of droplets 110. A predeterminedcurvature characteristic of the angled surface 106 results in a widerdistribution of the droplets 110 within an ejection angle 112. FIG. 18provides a front view of the curved member 100 and further illustratesthat the angled surface 106 is bound on its perimeter by a windowopening 114. Preferably, the angled surface 106 includes 45 apertures116 in a 5×9 matrix.

FIG. 19 is a schematic view of a fluid delivery system 224 forregulating the flow of liquid 226 to an oscillating surface 228 having aplurality of tapered holes (not shown) for dispensing liquid aspreviously described. The fluid delivery system 224 is configured sothat the volumes of liquid delivered to the oscillating surface 228 aresubstantially equal to the volumes of liquid ejected from theoscillating surface 228. The fluid delivery system 224 is furtherconfigured so that the liquid 226 is delivered to the oscillatingsurface 228 at a rate that is substantially equal to the rate ofejection from the surface 228.

The fluid delivery system 224 includes a central reservoir 230 forstoring the liquid 226 and a fluid channel 232 extending from thecentral reservoir 230. The fluid channel 232 has a distal end 234 thatis spaced apart from the oscillating surface 228. The fluid deliverysystem 224 further includes a gas or an air vent 236 having an opendistal end 238 that is near the distal end 234 of the fluid channel 232and is spaced apart from the oscillating surface 228. With such aconfiguration, the liquid 226 flows by force of gravity from the centralreservoir 230, through the fluid channel 232, and out the distal end234. As the liquid 226 is delivered to the oscillating surface 228, aliquid bead 240 is formed. The liquid 226 flows from the centralreservoir 230 until the bead 240 becomes large enough to occlude thedistal end 238 of the air vent 236. As the distal end 238 of the airvent 236 is filled with liquid from the bead 240, air is prevented fromflowing to the central reservoir 230 from the air vent 236, therebycreating a vacuum in the central reservoir 230 and preventing furtherfluid flow through the fluid channel 232. As liquid from the bead 240 isejected from the oscillating surface 228 in the manner previouslydescribed, the bead 240 is reduced in size allowing air to enter intothe vent 236 and allowing additional fluid to flow through the fluidchannel 232. In this manner, a continuous supply of liquid 226 isprovided to the oscillating surface 228 in amounts that aresubstantially equal in volume to the amount of liquid dispensed from theoscillating surface 228 and at a rate that is equal to the rate ofejection.

An alternative embodiment of a fluid delivery system 242 isschematically illustrated in FIG. 20. The fluid delivery system 242includes a central reservoir 244 and a fluid channel 246 that are bothfilled with a liquid 248. The fluid delivery system 242 operates underthe same principles as the fluid delivery system 224, i.e. bycontrolling air flow to the reservoir 244. Specifically, liquid 248flows through a distal end 250 of the fluid channel 246 by capillaryforces to form a liquid bead 252 on an oscillating surface 254. An airvent 256 is provided in the fluid channel 246 for supplying air to thecentral reservoir 244. As the liquid 248 travels through the fluidchannel 246 to reach the oscillating surface 254, some of the liquid 226flows into the air vent 256 to close the air vent 256. At this point,air is prevented from flowing into the central reservoir 244 via the airvent 256, thereby creating a vacuum in the reservoir 244 and stoppingthe flow of liquid 248 from the central reservoir 244. As liquid fromthe bead 252 is ejected from the oscillating surface 254, fluid isdrained from the air vent 256 and flows toward the distal end 250 toreplace the liquid ejected. As the fluid is drained from the air vent256, the air vent 256 is opened to allow air to flow through the fluidchannel 246 and into the central reservoir 244. An amount of liquid 248equal in volume to the volume of air supplied to the central reservoir244 via the air vent 256 then flows through the channel 246 to againfill the air vent 252 and to resupply liquid ejected from the bead 252.By tailoring the dimensions of the fluid delivery system 242, the volumeof air entering the reservoir 244 can be easily controlled so that acontinuous supply of liquid 248 is supplied to the oscillating surface254 in an amount equal in volume the amount of the liquid dispensed fromthe oscillating surface 254 and at a rate equal to the rate of ejection.

Referring to FIG. 21, an exemplary embodiment of an apparatus 260 fordispensing liquid as an atomized spray is shown in perspective view. Theapparatus 260 is patterned after the delivery system 242 of FIG. 20 andis particularly useful for relatively small flow rates, i.e. millilitersper hour. The apparatus 260 includes a vibratable member 262 that isconnected to a housing 264. Within the housing 264 is an ultrasonictransducer element (not shown) for vibrating the member 262 at anultrasonic frequency. At a distal end 266 of the member 262 is anaperture plate 268 having a plurality of apertures (not shown) fordispensing liquid when the member 262 is vibrated. The apertures in theplate 268 are tapered with the apertures having a larger cross-sectionalarea at a rear surface 269 (see FIG. 22B) of the vibratable member 262.The rear surface 269 in turn faces a holding surface 270 on theapparatus 260. The aperture plate 268 is preferably in contact with theholding surface 270, but can be spaced apart from the holding surface,usually by distances up to about 1.0 mm and sometimes greater.

As described in greater detail hereinafter, liquid on the holdingsurface 270 is supplied from a supply container 272. As liquid isdelivered to the holding surface 270, a thin layer of liquid isdeveloped on the holding surface 270. The liquid film is placed incontact with the aperture plate 268 so that upon vibration of the member262 liquid is ejected from the apertures in the plate 268 in the mannerdescribed with previous embodiments. The liquid is held to the rearsurface 269 of the plate 268 by surface tension forces. Preferably, thesurface tension forces will be the exclusive forces holding the liquidto the plate 268 until the liquid is ejected. In this way, liquid willnot overflow and spill from the holding surface 270 during operation.The supply container 272 is preferably removably attached to the housing264 so that new or different supplies of liquid can easily be providedby removing and refilling the supply container 272 or by providing a newcontainer 272.

Referring to FIGS. 22–23, delivery of liquid from the container 272 tothe holding surface 270 will be described. The housing 264 includes alongitudinal member 274, an insert 276, and a holding member 278. Theholding member 278 holds the vibratable member 262 over the holdingsurface 270 and includes the ultrasonic transducer for vibrating themember 262. As best shown in FIG. 23, the insert 276 is inserted into anelongate groove 280 in the longitudinal member 274 to form a fluid path282 extending between the longitudinal member 274 and the insert 276.The insert 276 is removably held within the longitudinal member 274.Configuring the connection between the longitudinal member 274 and theinsert 276 in this manner is advantageous for ease of manufacture. Thelongitudinal member 274 and the insert 276 can be made from partsmodified from a fountain pen, commercially available from Sheaffer Inc.,Ft. Madison, Iowa.

The fluid path 282 is formed by a groove 284 in the longitudinal member274 and a channel 286 in the insert 276. A proximal end 288 of the fluidpath 282 is in communication with the supply container 272, while adistal end 290 of the fluid path 282 is in communication with a slit 292in the longitudinal member 274. In turn, the slit 292 is incommunication with the holding surface 270. In this manner, liquid fromthe supply container 272 is delivered to the holding surface 270 via thefluid path 282 and the slit 292.

Referring to FIGS. 22A and 22B, configuration of the slit 292 will bedescribed in greater detail. The slit 292 preferably has a width that isnarrow enough to allow for liquid to be drawn through the slit 292 bycapillary forces. Preferably the width of the slit 292 is in the rangefrom about 0.002 inch to 0.005 inch, and more preferably at about 0.004inch. In this way, liquid reaching the distal end 290 of the fluid path282 is drawn through the slit 292 and to the holding surface 270 bycapillary action.

Referring to FIGS. 23, 24A, and 24B, regulation of the flow of liquidfrom the supply container 272 and to the holding surface 270 will bedescribed. In communication with the fluid path 282 is a gas or air vent294. The air vent 294 is formed in the longitudinal member 278 andallows air from the atmosphere to flow into the supply container 272 viathe fluid path 282. The supply container 272 is sealed about the housing264 so that the interior of the supply container 272 can onlycommunicate with the outside atmosphere via the fluid path 282. Asliquid is transferred from the supply container 272, a vacuum is createdwithin the container 272, thereby preventing further flow of liquid fromthe container 272 until the container 272 is vented. In this way, theflow of liquid from the container 272 and to the holding surface 270 isregulated by controlling the amount of air supplied to the container272.

The amount of liquid supplied to the holding surface 270 will preferablybe sufficient to cover at least a portion of holes of the aperture plate268 without overflowing from the holding surface 270 and creating amessy and wasteful working environment. Upon vibration of the apertureplate 268, some of the liquid is ejected from the holding surface 270.The ejected liquid is replaced with an equal amount of liquid,preferably at a rate that is equal to the rate of ejection. As describedbelow, delivery of liquid in this manner is accomplished by supplyingair to the container 272 in volumes that are sufficient to replace thevolumes of liquid delivered to the holding surface 270 and at a ratethat is equal to the rate of ejection.

Upon connection of the supply container 272 to the housing 264, fluidflows from the container 272 and into the fluid path 282. Preferably,the apparatus 260 will be elevated to have the container 272 above theholding surface 270 to allow gravity to assist in transferring liquidthrough the fluid path 282. The liquid flows through the fluid path 282until reaching the air vent 294. At this point, some of the liquidbegins filling the air vent 294 while the remainder continues throughthe fluid path 282 and to the slit 292. The liquid that reaches the slit292 is drawn by capillary action through the slit 292 and to the holdingsurface 270. At the same time, the air vent 294 continues to fill withliquid until sufficient liquid is within the air vent 294 to close thevent 294 and prevent air from the atmosphere from entering into thesupply container 272. With no air entering the supply container 272, avacuum is created within the container 272, thereby preventing furtherflow of liquid from the container 272.

The size, length, and relative orientation of the supply container 272,the fluid path 282, the slit 292, and the air vent 294 can be varied totailor the amount of liquid reaching the holding surface 270. Theparticular configuration of these elements can be experimentallyobtained based on the properties of the liquid involved. In onepreferable aspect, the air vent 294 has a width in the range from 0.002inch to 0.003 inch, a length in the range of about 0.005 inch to 0.010inch, and is distanced from the supply container 272 by a length ofabout 0.5 inch when used with a supply container 272 having a volume ofabout 2 cm³.

Upon vibration of the vibratable member 262, the liquid initiallysupplied to the holding surface 270 is ejected from the aperture plate268. As liquid is ejected from the holding surface 270, additionalliquid is drawn through the slit 292 by capillary action to replace thedispensed liquid. As liquid is drawn through the slit 292, liquid in theair vent 294 drains into the fluid path 282 to replace the liquid. Whenliquid drains from the air vent 294, the air vent 294 reaches an openconfiguration to allow air to enter into the vent 294 where it travelsto the supply container 272 via the fluid path 282. Delivery of air tothe container 272 in this manner reduces the amount of vacuum existingin the container 272 and allows an amount of liquid to be transferredinto the fluid path 282 until the threshold vacuum pressure is againreached in the container 272. As fluid is transferred into the fluidpath 282, the air vent 294 again closes as previously described. Hence,by tailoring the configuration of the dispensing apparatus 260, acontinuous supply of liquid can delivered to the holding surface 270 forejection by the aperture plate 268 in an amount that is substantiallyequal to the amount dispensed and at a rate that is equal to theejection rate. This ensures that sufficient (but not excessive) fluidwill be supplied to the aperture plate 268 for ejection.

The housing 264 will preferably be constructed of a plastic materialhaving good surface wetting capabilities, such as ABC plastic, andparticularly, Cycloac. To assist the flow of liquid through the fluidpath 282 and the slit 292, a small amount of liquid surfactant can beadded to the liquid. The apparatus 260 can be employed to dispense avariety of liquids such as water, ink, alcohol, gasoline, deodorants,insecticides, medicaments, and other liquids having applications whereatomization of the liquid is needed.

One particular advantage of the apparatus 260 is that the flow of liquidfrom the supply container 272 to the aperture plate 268 is controlledwithout the use of the moving elements, electrical circuits, mechanicalvalves, or the like. Instead, the flow of liquid is controlled by theliquid itself as the liquid fills and is drained from the air vent 294.Such an apparatus is easy to manufacture, use and to refill with newliquid, thereby reducing purchase and maintenance costs and providingconvenience.

Referring to FIGS. 25 and 26, an alternative embodiment of an exemplarydispensing apparatus 300 will be described. The apparatus 300 includes ahousing 302 that is separable into two halves. The housing 302 isprovided with at least one ejection port 304 for ejecting liquid 306.The housing 302 further includes an application port 308 for attaching asupply of liquid.

Within the housing 302 is a vibratable member 310 having an apertureplate 312 mounted therein. The aperture plate 312 is aligned with theejection port 304 so that liquid ejected from the aperture plate 312 isdispensed through the ejection port 304 as illustrated in FIG. 25. Theaperture plate 312 includes a plurality of tapered apertures similar tothe aperture plates previously described. Circuitry 313, including atransducer, is provided for vibrating the vibratable member 310 so thatliquid can be dispensed through the apertures in the aperture plate 312as previously described.

To supply liquid to the aperture plate 312, a liquid delivery system 316is provided. The liquid delivery system 316 is preferably verticallyangled in the housing 302 so that gravity can assist in the flow ofliquid toward the aperture plate 312. The liquid delivery system 316 canbe essentially identical to the dispensing apparatus 260 described inFIG. 21. The circuitry 313 further includes an electronic timer forcyclically actuating the transducer 314. To provide power to thetransducer 314, the apparatus 300 further includes a pair of batteries318, such as commercially available AAA-type batteries.

By configuring the dispensing apparatus 300 as just described, a numberof advantages are provided. Use of the batteries 318 as a power sourceallows the dispensing apparatus 300 to be placed in a wide variety oflocations (particularly remote locations where conventional poweroutlets are not available). For example, in one preferable aspect, thedispensing apparatus 300 is useful as an insecticizer. Use of thebatteries 318 allows the apparatus 300 to be placed in remote locations,such as in an attic, near a patio, in a garage, or the like.

A further advantage of the dispensing apparatus 300 is that it can bepreprogrammed with a dispensing cycle, e.g. ejecting liquid five secondseach five minutes. In this way, the ejection of liquid can be programmedto precisely control the amounts of liquid that are dispensed into theatmosphere. Programming the apparatus 300 in this way is desirable inmany applications where safety is a concern and precise control of theamount of liquid dispensed is critical. As one example, the dispensingapparatus 300 is useful in controlling the dispensing of an insecticidesuch as a pyrethroid insecticide sold under the name Sumithrin. Byprogramming the apparatus 300 with a dispensing cycle, safety isprovided by ensuring that too much insecticide will not be dispensed,particularly when used near inhabited locations. At the same time,programming allows a sufficient amount of liquid to be ejected so thatthe apparatus 300 is effective as an insecticizer. Reliability is alsoprovided since regulation of the flow of liquid to the aperture plate312 is provided by an air vent and involves no moving or electricalparts.

As one example, which is not meant to be limiting, when used as aninsecticizer, the apparatus 300 preferably dispenses the insecticide ata rate in the range from 0.5 cm³ to 2 cm³ per hour, with droplet sizesbeing in the range from 3 micron to 10 micron. Usually, the vibratablemember is vibrated at a frequency in the range from 20 kHz to 200 kHz.When used as an air freshener, the apparatus 300 preferably dispensesthe air freshener at a rate in the range from 1 cm³ to 2 cm³ per hour,with droplet sizes being in the range from 3 micron to 10 micron.

In still a further advantage, the dispensing apparatus 300 is relativelyinexpensive to manufacture and operate thereby providing a convenientalternative to a consumer in his choice of dispensing apparatus. Forexample, operating costs usually only include the cost of batteries andthe liquid. In one alternative, the batteries can conveniently beincluded as part of the supply container so that each time a newcontainer is connected to the port 308, the batteries are replaced. Thisallows the batteries and the liquid supply container to be sold togetheras a single disposable unit.

It will now be understood that what has been disclosed herein comprisesa novel and highly innovative fluid-ejection device readily adapted foruse in a variety of applications requiring the ejection of smalldroplets of fluid in a precisely controlled manner.

Those having skill in the art to which the present invention pertainswill now, as a result of the Applicant's teaching herein, perceivevarious modifications and additions which may be made to the invention.By way of example, the shapes, dimensions, and materials disclosedherein are merely illustrative of a preferred embodiment which has beenreduced to practice. However, it will be understood that such shapes,dimensions, and materials are not to be considered limiting of theinvention which may be readily provided in other shapes, dimensions, andmaterials.

1. A droplet ejector device, comprising: a vibratable member having arear surface and a front surface, and a plurality of tapered aperturesthat taper inwardly from the rear surface to the front surface; acontainer that is configured to store a liquid that is to be supplied tothe rear surface of the vibratable member, wherein when the liquid is atthe rear surface the liquid is no greater than atmospheric pressure; avibratory element coupled to the vibratable member so as to be on atleast opposing sides of the vibratable member, wherein the vibratoryelement is actuatable to vibrate the vibratable member, and whereinvibration of the vibratable member is configured to eject liquiddroplets from the front surface when liquid is supplied from thecontainer to the rear surface.
 2. A device as in claim 1, wherein thevibratory element comprises a piezoceramic.
 3. A device as in claim 1,wherein the apertures taper from about 0.006 inch to about 0.0025 inch.4. A device as in claim 1, wherein the vibratory element is configuredto vibrate the vibratable member at a frequency of about 60,000 Hz orgreater.
 5. A method for ejecting liquid droplets, the methodcomprising: providing a vibratable member having a rear surface and afront surface, and a plurality of tapered apertures that taper inwardlyfrom the rear surface to the front surface; supplying an amount ofliquid to the rear surface of the vibratable member, wherein when theliquid is at the rear surface the liquid is at no greater thanatmospheric pressure; vibrating the vibratable member with a vibratoryelement that is coupled to the vibratable member so as to be on at leastopposing sides of the vibratable member, wherein the vibratable memberis vibrated while the liquid is at the rear surface to cause liquiddroplets to be ejected from the front surface.
 6. A method as in claim5, wherein the liquid is supplied to the rear surface from a container.7. A method as in claim 5, further comprising controlling the amount ofliquid supplied to the rear surface.
 8. A method as in claim 5, furthercomprising vibrating the vibratable member with a piezoceramic at afrequency of about 60,000 Hz or greater.
 9. A method as in claim 5,wherein the apertures taper from about 0.006 inch to about 0.0025 inch.10. A method as in claim 5, further comprising vibrating the vibratablemember under different pressure conditions.
 11. A method as in claim 5,wherein the liquid comprises a medicament.
 12. A droplet ejector device,comprising: a vibratable member having a rear surface and a frontsurface, and a plurality of tapered apertures that taper inwardly fromthe rear surface to the front surface; a container that is configured tostore a liquid that is to be supplied to the rear surface of thevibratable member, wherein when the liquid is at the front surface theliquid is at no greater than atmospheric pressure; a vibratory elementcoupled to the vibratable member, wherein the vibratory element isactuatable to vibrate the vibratable member, and wherein vibration ofthe vibratable member is configured to eject liquid droplets from thefront surface when liquid is supplied from the container to the rearsurface; and an intermediary member that is coupled to the vibratablemember, and wherein the vibratory element is also coupled to theintermediary member.